Improvement in dovetail tenon and-mortise joints for joinery



R. B. CANTRELL.

DOVE'I'AIL TENON AND MORTISE JOINTS FOR J'OINERY.

Patented March 6,1877.

A R a o u T u w o M P s a n J N UNITED STATES -PA'IENT ROBERT E.OANTRELL, OF BROOKLYN, NEW YORK.

IMPROVEMENT IN DOVETAIL TENON AND-MORTISE JOINTS FOR JOINERY.

Specification forming part of Letters Patent No. 187,962, dated March 6,1877; application filed December 27, 1876.

To all whom it meg concern:

Be it known thatjfI, ROBERT. B. GANTRELL, of Brooklyn, New. York, haveinvented certain new and useful Improvements in Dovetail 'Te'non andMortise'Joints for Joinery, of which the following is a specificationThe dovetail joint so extensively used in carpentry and joinery onaccount of its solidity and durability is in woodworking one of the mostdifficult things to make, for unless its adjustment. and fit areperfect, or nearly so, it

will not answerits purpose. Its application also is necessarily limitedto pieces which, to be joined, have the dovetail tenon and mortise ontheir ends, and show the same when united on theface ofthe work, for itis obvious, a dovetail tenon being larger on' the outer end than theopening of the mortise, it is impossible to introduce thetenon into themortise in the manneuas ordinary tenons are, '5. 0.,

lengthwise, butmust be introduced into the mortise sidewise, and thusalways must show thejoint. f

The object of this invention is twofold first, the formation of adovetail-tenon joint inwhich the tenon and the mortise shall moretightly and accurately fit than this can be done by theordinary mode ofconstruction; secondly, the application of dovetailtenon joints to workto which heretofore it could not be applied-that is to say, in placeswhere thetenon is inclosed on all sides by its corresponding mortise.These objects I have attained and accomplished by simply compressing thetenon, previous to insertion into the mortise, and by subsequentlyexpanding the same to its natural size, or to the dimensions to which ithas been designed and out.

To enable others to make and use my said invention I shall now proceedto describe the same with reference to the accompanying drawing, inwhich- Figure 1 represents an isometric-a1 perspective view of a door orsash madein accordance with my said invention. Fig. 2 shows, in section,various examples or forms of dovetailtenon joints,formed on the end ofcross-pieces, and inserted into an upright piece having correspondingmortises. Figs. 3 and 4 represent, respectively, in perspective andvertical section, an apparatus which is or may be used for thecompression of the dovetail tenons, as hereinafter shown and described.

To practically explain my invention I shall describe it as applied tothe manufacture of doors or sashes, or other like frame. As heretoforemade, the several pieces composing the frame were united by common tenonand mortise joint. To prevent their parting, care is taken to drive infrom the outside, and between the outer end of the tenon and themortise, small wedges or pegs.

In the course of time, as the wood becomes more seasoned and shrinks,these wedges or pegs are apt to become loose and work out, and thuseventually open the joints of the door and allow for the settling on oneside or the other, or, as the term is, to get out of square. By mymethod of making such frames I cut into the uprights A dovetail-shapedmor tises--that is, recesses, which are larger in the bottom than at theentrance, as shown at a, b, c, d, e, and f. Upon the ends of thecrosspieces B, in lieu of the ordinary tenons, I cut dovetail tenonsthatis, a tenon which is deeper on the outsidejthan on the inner end, but ofthe same width or thickness as the mortise. To introduce these tenonsinto their respective mortises I compress them. in an apparatus suitablefor the purpose, which will allow for the condensation of the fiberacross the depth of the tenon, without, however, allowing it to expandsidewise. Such an apparatus is shown in Figs. 3 and 4, which consists ofa quadrangular box, 0, composed of two side plates, g g and g g, unitedat their opposite ends by an end piece, h. In the side plates are formedtwo rectangular slots, '5 t, which contain the pivotal axis of acompression-lever, k. A'fulcrum-pin, l, is provided at the upper angle,opposite the end piece h. The two side plates are a distance apart equalto the width or thickness of the tenon, and the slot is of suchdimension that when the pivotal axis is in the most distant corner fromthe end plate, the space between the compression-lever and the said endplate will be such as to admit of the insertion of the tenon into thebox, while, when the pivotal axis is at the other extreme corner of theslot, the distance between the pivotal end of the compression-lever andthe end plate will be equal to the reduced or inner end of the dovetail.In connection with this box I use a cam-lever, G, of the construction asshown in the drawing. In order to compress the tenon I insert it intothe box, the lever k occupying the position indicated in Fig. 3. Thecompressionlever is now set to adapt itself to the face m of the tenon,by shoving the pivotal end toward the tenon and upward, lodging it intothe upper corner of the slot. The hooked end of the cam is now broughtto bear on the fulcrum-pin l, and by raising the lever (or by depressingit if the hook be upward) the compression-lever will be moved, and thetenon compressed until the sides of the tenon become parallel, or, forconvenience to introduce it into the mortise, slightly tapering. Thecompression having been thus effected, the dovetail-tenoned piece isinserted into the corresponding mortise, where it is made to expandagain to its original shape by the application of moisture or steam. Avery perfect joint is thus made, even if the dovetail is not cut withthe usual accuracy, and I deem it preferable to make the tenon in depthslightly exceeding that of the mortise, so that when expanded it willcompletely fill and more tightly fit the mortise than could be done byordinary dovetail joints, however accurately cut.

It will be observed that this mode of joining two pieces of woodtogether need not necessarily show on the outside of the work any partof the joint. The mortise may be out in one of the pieces. as shown atL, in the depth of the wood, and the tenon, when inserted, will besurrounded on all sides by unbroken texture of the wood. This modeadmits also of diiferent forms of dovetail tenons and mortises, as shownin Fig. 2, M representing a semi-dovetail-that is, an inclined facebeing cut on one side, leaving the other flush with the piece itself. Nshows an inclined plane between two portions of an ordinary tenon,having different depths. O is a double-shouldered, and P asingle-shouldered,tenon. B shows a combined ordinary tenon and dovetailtenon.

In Fig. 5 1 show another application of my invention, whereby a mortisemay be cut in each of two pieces to' be united, and a double dovetailpiece, compressed to the shape indicated in dotted lines, inserted andswelled as above, constituting a perfect anchor, and rendering thepieces inseparable short of rupture.

It may be preferable, in some cases, to take off the extreme outercorners of the dovetail tenon to allow the tenons to be entered moreeasily into the mortise, and to obviate the danger of chipping off theedges of the tenon when being forced into the mortise. This may beparticularly desirable when several tenons are to be introducedsimultaneously into corresponding mortises, as I have found by practicalobservation that with some woods, and at certain seasons, when theatmosphere is damp, the tenons are apt to spring back, or swell soquickly that before the last tenon was compressed the first had alreadyswelled and become too large to be introduced into the mortise. 7

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

1. The employment and use in joinery of compressed dovetailed-tenonjoints, substantially as herein shown and described.

2. The method herein described of compressing dovetailed tenons forsubsequent expansion in corresponding mortises.

3. Doors, sashes, and other analogous work of joinery or carpentry, theseveral pieces of which are united or joined together by means ofcompressed dovetail tenon joints, substantially as herein shown anddescribed.

In testimony whereof I have hereunto signed my name this 5th day-ofDecember, A. D. 1876.

Witnesses: ROBT. B. GANTRELL.

T. LLoYn DALTON, I). VAN WART.

